The prior art has addressed the need to measure photographic properties of silver halide emulsions in order to provide and to consistently maintain the desired photographic properties in such emulsions. One of the methods used for such measurement is a sensitrometric method in which a part of the photographic emulsion is coated on a support or carrier, dried, exposed for development, fixed, and the blackened density of the layer is measured sensitometrically. If the so-produced layer does not have the desired photographic properties, the emulsion is generally referred to as being "fogged". This method is time consuming and its success is largely dependent on the skill of the operator performing the testing. In addition, much time, effort and materials are wasted if the emulsion is fogged.
Another method, disclosed by U.S. Pat. No. 5,212,098, involves titrating of bromide ions present in a non-chromogenic developer containing thiocyanate ions with an aqueous silver nitrate. The method is relatively cumbersome and time consuming.
Still another approach for measuring the progress of the development of liquid photographic emulsions is exemplified by U.S. Pat. No. 3,864,082. This approach comprises a method in which the liquid photographic emulsion is mixed with a developer in a tank, and the emulsion is caused to react with the developer to form reduced silver. Without adding a fixing solution or a stopping solution, the mixture is introduced into a flow cell, and passed through the flow cell for the period of time necessary for measurement. In the flow cell, the mixture is irradiated by light to quantitatively measure the amount of reduced silver using optical means.
While this approach monitors the emulsion, the mixing operation, measurement and the washing/cleaning of the tank and flow cell can influence the outcome of the measurements. Accordingly, it is desirable to test a photographic batch of an emulsion after formulation. It is further desirable to test the emulsion before coating the emulsion onto a support web or paper, since if the emulsion is fogged, materials, effort, and time would be wasted. Such waste could be prevented by testing the emulsion before coating onto the support web or paper.
It is also highly desirable to test photographic emulsions in white-light conditions for ease of operation.
The present invention addresses the needs not quite satisfactorily met by the prior art by providing a consistent, reliable apparatus, and method of use thereof, for measuring photographic properties of an emulsion after formulation and prior to coating the emulsion onto a support, and in white-light conditions.